My horse (16.1 hh warmblood) has been tearing his boots off in turnout. He has figured out that he can lift his leg and then bite the boot to tear it off, so if anyone has recommendations for sturdy turnout boots that'd be much appreciated!

Do you mean bellboots? The best are just rubber pull-ons. They're a bitch to get on and off but harder for the horses to mess with.

I would make the same recommendation. Make sure to have back pairs handy! Your horse may also do better by wearing 2 sets of bell boots, one on top of the other, so that when one is ripped off another is still there.

Thank you! I would love splint boot recommendations too lol

Have you tried just taping over the straps?

Oooo! Thank you!

If your horse is taking splint boots off, wrap some duct tape around those bad boys to cover the straps in a layer. It's simple to snip or peel of the tape when you need to take them off. It's also impossible for the horse to get a grip on the tape. My horses pasture all the time and only wear the boots when riding, so I've never had an issue with them taking them off, but I have a couple that rub their faces on their front legs if they want to scratch itches, and they occasionally see the boots as something that's annoying them.

Why do you need the boots?

This was going to be my question as well. Unless there is a really pressing need for some reason (and IMO using the boots as a pseudo bubble wrap for the "what ifs" doesn't count), I'd just turn out without boots. I don't mean that to be harsh but the boots clearly annoy your horse in turnout to the point he's figured out how to remove them...I see turnout as their "me" time and unless he truly needs them for some reason, I'd just turnout without.